Systems and methods for providing a multi-perspective video display

ABSTRACT

Methods and systems for providing a multi-perspective video display are presented. In one example, a program of visual content that includes a plurality of visual perspectives is received. A first one of the plurality of visual perspectives is displayed on a display device, and a second one of the plurality of visual perspectives is displayed on the display device during the displaying of the first one of the plurality of visual perspectives.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/765,965, titled “SYSTEM AND METHOD FOR PROVIDING MULTI-PERSPECTIVEINSTANT REPLAY,” filed Jan. 19, 2001, which claims the benefit ofpriority of U.S. Provisional Application No. 60/235,529, titled “SYSTEMAND METHOD FOR PROVIDING MULTI-PERSPECTIVE INSTANT REPLAY,” filed Sep.26, 2000, each of which is hereby incorporated herein by reference inits entirety.

Each of U.S. patent application Ser. No. 09/630,646, titled “SYSTEM ANDMETHOD FOR INCORPORATING PREVIOUSLY BROADCAST CONTENT,” filed Aug. 2,2000, and U.S. Provisional Patent Application No. 60/162,490, titled“RECORDING OF PUSH CONTENT,” filed Oct. 29, 1999, is hereby incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to interactive video deliverymediums such as interactive television, and more particularly, to asystem and method for providing multi-perspective instant replay ofbroadcast material.

A broadcast service provider transmits audio-video streams to a viewer'stelevision. Interactive television systems are capable of displayingtext and graphic images in addition to typical audio-video programs.They can also provide a number of services, such as commerce via thetelevision, and other interactive applications to viewers. Theinteractive television signal can include an interactive portionconsisting of application code, data, and signaling information, inaddition to audio-video portions. The broadcast service provider cancombine any or all of tins information, into a single signal or severalsignals for transmission to a receiver connected to the viewer'stelevision or the provider can include only a subset of the information,possibly with resource locators. Such resource locators can be used toindicate alternative sources of interactive and/or audio-videoinformation. For example, the resource locator could take the form of aworld wide web universal resource locator (URL).

The television signal is generally compressed prior to transmission andtransmitted through typical broadcast media such as cable television(CATV) lines or direct satellite transmission systems, informationreferenced by resource locators may be obtained over different media,for example, through an always-on return channel, such as a DOCSISmodem.

A set top box connected to the television controls the interactivefunctionality of the television. The set top box receives the signaltransmitted by the broadcast service provider, separates the interactiveportion irons the audio-video portion, and decompresses the respectiveporticos of the signal. The set top box uses interactive information toexecute an application while the audio-video information is transmittedto the television. Set top boxes typically include only a limited amountof memory. While this memory is sufficient to execute interactiveapplications, it is typically not adequate to store the applications foran indefinite period of time. Further, the memory of the set top box istypically too small to accommodate a program which includes largeamounts of audio or video data, application code, or other information.Storage devices may be coupled to the set top box to provide additionalmemory for the storage of video and audio broadcast content.

Interactive content such as application code or information relating totelevision programs is typically broadcast in a repeating format. Thepieces of information broadcast in this manner form what is referred toas a “carousel”. Repeating transmission of objects in a carousel allowsthe reception of those objects by a receiver without requiring a returnpath from the receivers to the server. If a receiver seeds a particularpiece of information, it can simply wait until the next time that pieceof information is broadcast, and men extract the information from thebroadcast stream. If the information were not cyclically broadcast, thereceiver would have to transmit a request for the information to theserve, thus requiring a return path. If a user is initially notinterested in fee carousel content, but later expresses an interest, theinformation can be obtained the next time the carousel is broadcast.Since broadcast networks have access only to a limited bandwidth,audio-video content is not broadcast in carousels. There is alsoinsufficient bandwidth and server resources to handle pulling of largeamounts of data required for video and audio in real-time to handle nearsimultaneous requests for broadcast of previously broadcast materialfrom a vast number of television viewers.

In a broadcast by a television network, such as a broadcast of asporting event, the content provider may generate multiple video feedsfrom various angles of the game, for example. The network may select oneor more feeds from the multiple video feeds and broadcast the selectedvideo feed(s) to the viewing audience at any given point in time. Thatis, the network my simultaneously broadcast video tracks that presentthe same scene, except from a different perspective or send differentaudio tracks or subtitles if a movie is broadcast in differentlanguages, for example. The viewer may use an interactive applicationthat executes on their set top box to choose between differentperspectives. When a viewer requests a change in perspective, theinteractive application uses meta-data to determine which packetscontain the chosen perspective. It starts delivering packets thatcontain the newly chosen perspective.

As previously described, a viewer cannot request previously broadcastaudio or video material due to the limited bandwidth available onbroadcast networks. Also, data that accompanies interactive applicationssometimes corresponds to audio and video that is currently beingbroadcast so it changes frequently. In these cases, the values broadcastas part of the carousel often change and old values are no longercarried in the carousel. Thus, a viewer cannot replay a scene or asporting event play from a different perspective unless the viewer hasalready recorded the video stream for the alternate perspective.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the distribution of television programsand signaling information from a broadcast station to a receivingstation.

FIG. 2 is a block, diagram of a system of the present invention forrecording programs received front the broadcast station of FIG. 1.

FIG. 3 is a block diagram illustrating the transfer of data to a storagedevice coupled to the set top box of FIG. 2.

FIG. 4 is a diagram illustrating three video streams and two audiostreams simultaneously sent to a receiving station with one of the audioand one of the video streams sent to a television. Those same streamsare also sent to a storage device along with one of the other videostreams.

FIG. 5 is similar to the diagram of FIG. 4 except that the second videostream is now also displayed in a PIP window along with the first audioand video streams which are displayed in the main picture of thetelevision.

FIG. 6 is a diagram similar to the diagram of FIG. 5 except that thesecond video stream is now shown in the center of the television screenwith the first video stream, shown in the PIP window.

FIG. 6 a is a diagram, similar to the diagram of FIG. 6 except that theconfiguration shown does not require or use a PIP.

FIG. 7 is a diagram similar to the diagram of FIG. 6 except that thelive broadcast of the second video stream is replaced with a previouslybroadcast version of the same perspective.

FIG. 7 a is a diagram similar to the diagram of FIG. 7 except that theconfiguration shown does not require or use a PIP, and a recorded audiostream is played instead, of a live audio stream as in FIG. 7.

FIG. 8 is a diagram illustrating a first video stream and audio streamdisplayed on a television and recorded along with a second audio stream.

FIG. 9 is a diagram similar to the diagram shown in FIG. 8 except thatthe first audio stream is replaced with the second audio stream.

FIG. 10 is a diagram similar to the diagram of FIG. 9 except that thefirst video stream and second audio stream are replaced with earlierbroadcast versions.

FIG. 11 illustrates an example of files and data structures on a storagedevice. The text accompanying FIG. 11 describes how these datastructures could be used to facilitate the viewing of an instant replayfrom a different perspective.

FIG. 12 is a flowchart, of a method in accordance with the invention.

Corresponding reference characters indicate corresponding partsthroughout the several, views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following description is presented to enable one of ordinary skillin the art to make and use the invention. Descriptions of specificembodiments and applications are provided only as examples and variousmodifications will be readily apparent to those skilled in the art. Thegeneral principles described herein may be applied to other embodimentsand applications without departing from the scope of the invention.Thus, the present invention is not to be limited to the embodimentsshown, but is to be accorded the widest scope consistent with theprinciples and features described herein. It will be understood by oneskilled in the art that many embodiments are possible, such as the useof a computer system and display to perform the functions and featuresdescribed herein. For purpose of clarity, the invention will bedescribed in its application to a set top box used with a television,and details relating to technical material that are known in thetechnical fields related to the invention have not been included.

Referring now to the drawings, and first to FIG. 1, a diagram of atelevision broadcast and receiving system is shown and generallyindicated at 10. The system 10 includes a broadcast station 20 whereaudio-video and control information is assembled in the form of digitaldata and mapped into digital signals for satellite transmission to areceiving station. Control information such as conditional accessinformation and signaling information (such as a list of servicesavailable to user, event names, and schedule of events (start time/dateand duration), and program specific information) may be added, to video,audio, and interactive applications for use by the interactivetelevision system. Control information can describe relationshipsbetween streams, such as which streams can be considered as carryingdifferent perspectives of which other streams. The control informationis converted by the broadcast station, to a format suitable fortransmission, over broadcast medium. The data may be formatted intopackets, for example, which can be transmitted over a digital satellitenetwork. The packets may be multiplexed with other packets fortransmission. The signal is typically compressed, prior to transmissionand may be transmitted through broadcast channels such as cabletelevision lines or direct satellite transmission systems 22 (as shownin FIG. 1). The Internet, telephone lines, cellular networks, fiberoptics, or other terrestrial transmission media may also be used inplace of the cable or satellite system for transmitting broadcasts. Thebroadcaster may embed service information in the broadcast transportstream, and the service, information may list each of the elementarystream identifiers and associate with each identifier an encoding thatdescribes the type of the associated stream (e.g., whether it containsvideo or audio) and a textual description of the stream that can beunderstood and used by the user to choose between differentperspectives, as described below.

The receiving station includes a set top box 16 connected, to a storagedevice 18, and a television 20 which is used to present programs to aviewer. The set top box 16 is operable to decompress the digital dataand display programs to a viewer. The decompressed, video signals may beconverted into analog signals such as NTSC (National TelevisionStandards Committee) format signals for television display. Signals sentto the set top box 16 are filtered and of those that meet the filteringrequirements, some are used by the processor 30 immediately and otherscan be placed in local storage such as RAM. Examples of requirementsthat would need to be filtered for include a particular value in thelocation reserved for an elementary stream identifier or an originatingnetwork identifier. The set top box 16 may be used to overlay or combinedifferent signals to form the desired display on the viewer's television20.

As further described below, the set top box 16 is configured to recordone or more video and/or audio streams simultaneously to allow a viewerto replay a scene which has recently been viewed or heard by a viewer,except torn a different perspective. Broadcast station 12 simultaneouslybroadcasts multiple perspectives for use by viewers that have set topboxes 16 which execute interactive television applications. For example,multiple cameras may be used to record a sporting event and the stationmay broadcast from the multiple cameras at the same time to allow theviewer to choose between different camera views using an interactiveapplication that executes on their set top box 16. A broadcaster mayalso send multiple perspectives of audio tracks in different languages,for example. The multiple video and audio perspectives are only examplesof types of perspectives of which a plurality may be contained in abroadcast. Other examples include multiple teletext streams, perhaps indifferent languages; multiple executable, perhaps each meant for adifferent skill level; or multiple data streams. The present inventionallows a viewer to replay the same scene from a different perspective,while ensuring that the viewer will still be able to view, eithersimultaneously or at a later time, the portion of the program beingbroadcast simultaneously with their viewing of the replay. The viewermay request a replay of any combination of audio, video, executables,and data, from either the same or different perspectives as theperspectives previously played.

It is to be understood that the term, “program” as used herein refers toany broadcast material including television shows, sporting events, newsprograms, movies, or any other type of broadcast material, or a segmentof the material. The material may include only audio, video, data, orany combination thereof. The program may be only a portion of atelevision show or broadcast (e.g., without commercials or missing aportion of the beginning or end) or may be more than one show, orinclude commercials for example. Furthermore, it is to be understoodthat the term “viewing” as used herein is defined such that viewing ofprogram begins as soon as a tuner begins filtering data corresponding toa program. If a viewer has tuned to a particular frequency prior to thebroadcast of a program, the beginning of the viewing preferablycorresponds to the beginning of the program. The viewing preferably endswhen the program, is complete or when the tuner is no longer filteringthe frequency corresponding to the program. Thus, the recording of aprogram coincides with the “viewing” of a program and the program isonly recorded when a timer is tuned to the station broadcasting theprogram. In the event that the television display is turned off after aviewer has started recording the program, as long as the tuner is tunedinto the station broadcasting the program and a recording of theinformation broadcast on the same frequencies as those used at the startof the viewing is being made, the viewing is said to continue. Theaudio-video signals and program control signals received by the set topbox 16 correspond, to television programs and menu selections that theviewer may access through a user interface. The viewer may control theset top box 16 through an infrared remote control unit a control panelon the set top box, or a menu displayed on the television screen, forexample.

It is to be understood that the system 10 described above and shown inFIG. 1 is only one example of a system used to convey signals to thetelevision 20. The broadcast network system may be different thandescribed herein without departing from the scope of the invention.

The set top box 16 may be used with a receiver or integrated decoderreceiver that is capable of decoding video, audio, and data, such as adigital set top box for use with a satellite receiver or satelliteintegrated decoder receiver mat is capable of decoding MPEG video,audio, and data. The set top box 16 may be configured, for example, toreceive digital video channels which support broadband communicationsusing Quadrate Amplitude Modulation (QAM) and control channels fortwo-way signaling and messaging. The digital QAM channels carrycompressed and encoded multiprogram MPEG (Motion Picture Expert Group)transport streams. A transport system extracts the desired program fromthe transport stream, and separates the audio, video, and datacomponents, which are routed, to devices that process the streams, suchas one or more audio decoders, one or more video decoders, andoptionally to RAM (or other form of memory or a hard drive. It is to beunderstood that the set top box 16 and storage device 18 may be analog,digital, or both analog and digital.

As shown in FIGS. 1 and 2, the storage device 18 is coupled to the settop box 16. The storage device 18 is used to provide sufficient storageto record programs that will not fit in the limited amount of mainmemory (e.g., RAM) typically available in set top boxes. The storagedevice 18 may comprise any suitable storage device, such as a hard diskdrive, a recordable DVD drive, magnetic tape, optical disk,magneto-optical disk, flash memory, or solid state memory, for example.The storage device 18 may be internal to the set top box 16 or connectedexternally (e.g., through an IEEE 1394-1995 connection) with either apermanent connection of a removable connection. More than one storagedevice 18 may be attached to the set top box 16. The set top box 16and/or storage device 18 may also be included in one package with thetelevision set 20.

FIG. 2 illustrates one embodiment of a system, of the present invention16 generally includes a control unit (e.g., microprocessor), main memory(e.g., RAM), and other components which are necessary to select anddecode the received interactive television signal. As shown in FIG. 2,the set top box 16 includes a front end 26 operable to receive audio,video, and other data from the broadcast station 12. The broadcastsource is fed into the set top box 16 at the front end 26, whichcomprises an analog to digital. (A/D) converter and timer/demodulators(not shown). The front end 26 filters out a particular band offrequencies, demodulates it and converts it to a digital format. Thedigitized output is then sent to a transport stage 28. The transport,stage 28 further processes the data, sending a portion of the data, toan audio-visual (AV) stage 34 for display and another portion, to thecontrol processor 30, and filtering out the rest of the data.

Control information, may also be recorded as broadcast along with theaudio-video data or may be first manipulated by software within the settop box 16. For example, broadcast CA (conditional access) informationmay be used to decrypt broadcast video. The original broadcast streams,or modifications of these streams may be optionally re-encrypted using aset top box key or algorithm prior to recording. The encrypted video mayalso be stored as received along with the broadcast CA information.Also, clock information may be translated to a virtual time system priorto recording. An MPEG-2 elementary stream may be de-multiplexed from anMPEG-2 transport stream, then, encapsulated as a program stream andrecorded.

FIG. 3 illustrates the transfer of data from the transport stage 28 tothe storage device 18. The storage device 18 typically contains aplurality of programs which have been recorded by a viewer. Therecordings of each perspective are associated with identifyinginformation that may have been copied or modified from the originalsignaling information. This identifying information may containbookkeeping information similar to that typically stored in audio/videofile systems or hierarchical computer file systems. The identifyinginformation may have various formats and content, as long as it providessufficient, information to allow the viewer, possibly interacting withthe system, to uniquely retrieve a particular recorded perspective. Theprograms may be identified with, an ID number and a start time and endtime. As described below, the storage may be defragmented periodicallyso that the programs are stored in a contiguous manner. Direct memoryaccess (DMA) is preferably used to send data from the transport stage 28to the storage device 18. The data that is seat to the control processor30 may include meta-data which describes the content of the audio-videodata streams and may also include application programs and correspondingdata that can be executed on the control processor in order to provideinteractive television.

A copy of data sent from the transport stage 28 to the AV stage 34 issent to the storage device 18 at the beginning of the viewing. The CPUin the control processor 30 configures a DMA controller to ensure thatthe data is written to a buffer that is allocated in the storage device18. The number of minutes of viewing data to be recorded, in the bufferis preferably selected by the viewer; however, the set top box may 16 bepreset with a default value such as fifteen minutes. The controlprocessor's CPU calculates the size of the buffer to allocate based uponthe number of minutes and the maximum speed at which bits in thetransport stream that the viewer is watching will be sent. This maximumspeed may be obtained from meta-data sent with the audio-video stream.When the end of the buffer is reached, the CPU in the control processoris interrupted, at which time it will re-configure the DMA controller tostart writing at the beginning of the buffer. This design is known as acircular buffer.

The buffer is preferably circular to allow contiguous recording andwriting over of previously recorded content. When the viewer changes thechannel or a TV event (e.g., television program ends) occurs, me centralprocessor's CPU will be interrupted. At this time, the CPU may allocatea new butter or mark the beginning of the new event in the originalbuffer. The automatic recording of a program and all related video,audio, and data streams in a storage device at the start of the programwithout any action by the viewer, allows the viewer to replay a portionof the program from a different perspective.

As previously described, the control processor 30 records themulti-perspective streams at a start of the program to store theperspectives in storage device 18. The perspectives will continue to berecorded and stored within the storage device 18 for a predeterminedperiod of time (e.g., 15 minutes). If a viewer decides to record theentire viewing after the start or the program, he will select a recordoption and the processor 30 will allocate space within the storagedevice 18. All perspectives will be recorded along with the program thatis being viewed. See e.g., U.S. patent application Ser. No. 09/630,646,entitled. “System and Method for Incorporating Previously BroadcastContent” and filed Aug. 2, 2000, which is incorporated herein byreference in its entirety.

The joining of the first and second recorded portions of any givenperspective in a common storage area may be implemented eitherphysically or virtually. A physical implementation may include copyingthe first recorded portion to a location where the second portion hasbeen recorded. A virtual implementation may include the modification ofa data structure stored in a storage device. In either case, a viewerwatching a replay of any perspective should not be able to detect thatthe two parts of the perspective were originally stored separately.Thus, the portions of the perspective may be physically contiguous orthe portions of the perspective may be stored separately in anon-contiguous format as long as the entire recorded program, can beplayed back in a continuous manner (i.e., viewer does not notice atransition between the playback of the first and second portions of theperspective).

It is to be understood that the recording of the entire program,including the plurality of perspectives, in the storage device 18 mayoccur without any action by the viewer. For example, if fits viewerrewinds (or performs a similar action on different types of storagemedia) a portion of one of the recorded perspectives to replay a scene,the entire program along with all of its multiple perspectives may berecorded in the storage device, since the viewer has shown interest inthe program.

The control information that is broadcast with the program preferablyindicates which streams are related to the viewed streams. The set topbox 16, by filtering on the appropriate identifiers in the broadcastMPEG-2 (or DSS or other encoding) packets can locate all relatedelementary streams. It sends the streams that the viewer is watching tothe television set 20 and records in me storage device 18 the content ofthese streams, along with the other related streams, including relatedvideo, audio, executables, and data. Meta-data that indicates themaximum hit rate for the streams may accompany the elementary ortransport streams. The format of the recorded streams may depend uponthe hardware support. For example, special purpose hardware inside theset top box 16 may support re-multiplexing of streams or concurrentreads and writes to the storage device 18, as is well known by thoseskilled in the art.

Broadcast data such as audio and video data, application code, controlsignals and other types of information may be sent as data objects. Ifthe program is to be consumed (i.e., presented to the viewer) thebroadcast data must be parsed to extract data objects from the stream.When the necessary data objects have been extracted, the program isplayed. For example, any applications that need to be executed arelaunched and any audio or video data that needs to be presented to theviewer is played. If the program is stored, the data objects axeextracted in the same manner, but they are stored instead of beingimmediately used to present the program. The recorded program is playedback using the stored data objects. The data objects may include “live”data which becomes obsolete if not consumed immediately. If this data isstored and used when the program is played back, the program will in atleast part, be obsolete. Thus, while most of the data objects may bestored as flies, live data objects may be stored as references in theprogram. When the program is played back, new live data corresponding tothe reference may be obtained and used in place of the data which waslive at the time the program was recorded. Thus, only temporally correctdata is used by the interactive application when it executes at a latertime. (See e.g., U.S. Provisional Patent Application No. 60/162,490entitled “RECORDING OF PUSH CONTENT” filed Oct. 20, 1999, which isincorporated herein by reference, for all purposes).

FIGS. 4-10 show the set top box 16 receiving three video and two audiostreams from the broadcast station 12. The signals are received from thebroadcast station 12 at the tuner in front end 26 and related streamsare sent to demultiplexer and processor 100. Video streams V1, V2 andaudio stream A1 are all related (e.g., video streams are differentcamera views of a sporting event and A1 is the sound track for theannouncer) and can be provided in a single transport stream. If all therelated streams are provided in one transport stream only one tuner 50is required. The set top box 16 may include multiple tuners 50 forrecording and displaying related streams broadcast in separate transportstreams. Related streams are preferably broadcast on a small number offrequencies so that a large number of tuners will not be required withinor attached, to the set top box 16. For example, a large number (e.g.,five) of video streams along with multiple audio steams, executableprograms, data, and control information may be multiplexed together on asingle frequency.

FIGS. 4-7 illustrate a case where a viewer requests a replay from adifferent perspective using a picture-within-picture (PIP) mode. If aviewer wants to see the replay from a different perspective, it can beviewed, in a PIP mode without requiring multiple tuners in the set topbox 16 or the television 20. The additional tuner is not required sinceone of the video or audio streams that had been previously recorded iscoming from the storage device 18. All streams shown are preferablymultiplexed on the same frequency. The video or audio can be delivered,directly to the AV stage 34 which is contained in 100 which itself isinside the set top box 16, and may be multiplexed with a transportstream that is being delivered via the tuner 50. Note that 100represents three components; (i) a demultiplexer; (ii) a processor thatdirects portions of the broadcast information to other components; and(iii) an AV stage that modulates when necessary (i.e. when thetelevision is analog). Alternatively, the viewer ear choose to view onlythe replay while the set top box 16 buffers, on the storage device 18,the live broadcast for later delivery, as described below with respectto FIGS. 8-10.

In FIG. 4, the broadcast station 12 is sending video streams V1 and V2containing two different perspectives and one audio stream A1. The twovideo streams may be two different camera positions at a baseball game,for example. The viewer is currently watching video stream V1 andlistening to audio stream. A1. The first and second, video streams V1and V2 and the audio stream A1 are automatically recorded. Thus, thepreviously broadcast information is available if a viewer warns toreplay, for example, the last play of the game. In particular, with thisinvention, the viewer can replay this information from any of thepreviously broadcast perspectives. The viewer may place the set top boxinto a PIP mode so that the viewer can see a first perspective (videostream V1) displayed in a large central area, in the television screenand a second perspective (video stream V2) displayed in a small picturewindow in the top right hand corner (or some other area) of thetelevision screen (FIG. 5). After an important play in the game (e.g.,double play in a baseball game), the viewer may want to see a replay,this time from a perspective different torn the one shown in V1. At thistime, the viewer may optionally switch, the windows into which the videostreams V1 and V2 are displayed, as shown in FIG. 6. Video stream. V1 isnow sent to the PIP window and video stream V2 is sent to the centralviewing window. Then the viewer would give a command (i.e. press abutton on the remote control) to re-wind the video in the main windowwhile permitting the PIP window to continue displaying the “live” V1 inthe PIP window.

As shown in FIG. 7, the recorded video stream V2′, which is from thesame perspective as V2, but which was broadcast and recorded earlier, issent from the storage device 18 to the demultiplexer in 100 which sendsthe previously recorded stream V2′ along with the current video streamV1 to the television for display. The viewer may rewind or searchthrough the recording until the beginning of the recording is reached.The viewer may also rewind and display the first video stream V1.Meanwhile the broadcast of the remainder of the program, may be sent tothe storage device 18 since the viewer has shown an interest in therecording. This may be automatic (i.e., program streams are sent tostorage device 18 upon a viewer's request for a replay) or may onlyoccur upon receiving a request from me viewer to record the entireprogram.

Alternatively, a viewer may prefer not to be distracted by the livebroadcast, which is shown as being displayed in the PIP in FIG. 7.Therefore, the viewer may simply first switch perspectives from V1 to V2as shown in FIG. 6 a. After that, the viewer may “rewind” to an earlierevent to see a previous scene from the perspective carried in videostream V2. This case is shown in FIG. 7 a where a copy of the live videostream V1 is only sent to the storage device, along with the live videostream V2 and live audio stream A1. The recorded streams V2′ and A1′ arethe only ones sent, possibly after modulation, to the television. Thescenario presented in FIGS. 6 a and 7 a could also be a scenario used bythe viewer to switch between a live video perspective and a different,recorded, video perspective, when there is no PIP functionalityassociated with the viewer's television.

FIGS. 8-10 illustrate a case where a program is broadcast with differentperspective audio streams. For example, a viewer may be watching anItalian movie that is broadcast with an Italian audio stream A1 and anEnglish audio stream A2. As shown in FIG. 8, video stream V1 and audiostream A1 are presented, to the viewer and recorded in the storagedevice 18 while audio stream A2 is also recorded in the storage device18 but not presented to the viewer. The viewer is initially listening tothe Italian broadcast (audio stream A1); however, during part of themovie, the viewer does not understand the Italian, so he selects a“switch to English” option from a menu and the viewer now hears theEnglish broadcast (audio stream A2) (FIG. 9). If the viewer wants tohear the soundtrack that accompanied the previous scene in English, hemay rewind the tape of the video stream V1 and audio stream A2 and watchthe scene over again in English (FIG. 10). The video and audio streamsV1, A1, and A2 will continue to be recorded so that the viewer can seethe rest of the movie in a deferred mode, without missing the portion ofthe movie that was broadcast while the viewer was rewinding andreplaying the previous scene.

FIG. 11 shows an example of a meta-data file that can be stored alongwith each recorded perspective. This invention does not require theformat shown in this figure, but the format is only used as an exampleof how meta-data can facilitate the playing of an instant replay from adifferent perspective. Each record of the meta-data file shown contains,among other possible fields, a time and an offset. In this example, aprogram clock reference is frequently, though not periodically,broadcast along with the video. When some of these clock referencevalues are received by the set top box, their value, along with theoffset into the recording of the most recent I-frame (one of 3 types ofMPEG-2 frame encodings that can be used for video), can be recorded asmeta-data. Again, this is only an example; an actual implementation maymake use of P- and B-frames (the other types of MPEG-2 encodings, bothof which are typically more compressed than an I-frame). The offset isin terms of bytes measured, from the beginning of the file containingthe recording of the perspective.

In this example, the viewer has been watching a live broadcast thatcontains video perspective V₁. As the viewer watches, that videoperspective, V₁ is being recorded to a file. Also, other videoperspectives, including video perspective V₂, are being recorded to adifferent file because they represent a different view of the sameinformation. Of course, V₂ could be recorded in the same file as long asother information distinguishing V₁ from V₂ is recorded, somewhere. Theviewer has just seen something interesting on the screen and enters theappropriate commands to cause V₁ to be re-wound to the beginning of theinteresting scene. The viewer stops V₁ when the MPEG-2 I-Frame_(1,t) isbeing used to display the contents of the screen. (Again, this is onlyan example. P- and B-frames could also be recorded in the filecontaining the I-frames from V₁, and could be used in locating a scene,but they are not used in this example, Also, MPEG-2 is only used as anexample; other formats of media and/or data can equally well be used)The viewer then Issues a command that tells the set top box to startplaying forward, but from V₂ rather than from V₁. The set-top box mustdetermine which I-frame of V₂ it should first cause to be displayed. Asimple solution, choosing tire I-frame nearest to the same offset asI-frame_(1,t) in the file that contains V₂ would only work, correctly ifboth perspectives were sent at the same constant rate, although such, anapproximation may be useful if the perspectives were sent atapproximately the same non-constant rate. A better solution for eithervariable-rate streams or streams with, different constant rates is nowpresented. This solution uses a linear interpolation, although otherwell-known classical interpolation methods that are readily available inthe open literature may provide a better approximation under somecircumstances.

First the actual time corresponding to the originally intended playingtime of I-frame_(1,t) is approximated. The offset into the filecontaining V₁ where I-frame_(1,t) is located, d_(1,t) is used for thisapproximation. In order to approximate this time, t, two consecutivetime values, d_(1,i) and d_(1,i+1), are searched for the meta-data file,such that d_(1,i)≦d_(1,t)<d_(1,i+1). (As a practitioner of the art wouldknow, a binary search would likely find these two consecutive elementsthe most quickly if the records are fixed length and the elements arestored in consecutive order as shown. A different search would beoptimal if a different storage format is used. Again, these are,well-known, techniques that are extensively documented in the computerscience literature.) Once they are located, both t_(1,i) and t_(1,i+1)will also be known. These values are then used to approximate t. Thisexample uses the linear interpolation formula:t=((t _(1,i+1) −t _(1,i))(d _(1,t) −d _(1,i))/(d _(1,i+1) −d _(1,i)))+t_(1,i)

After art approximation for t has been found, the location of theI-frame in the recording of perspective V₂ that is nearest to that timeneeds to be found, The first step here is to locate t_(2,k) andt_(2,k+1) such that t_(2,k)≦t<t_(2,k+1). Again, the search that performsthe best in any given case is dependent upon the format of the file andis a well-studied problem. Having these values allows for anapproximation of d_(2,)t. Once again, this example uses linearinterpolation:d _(2,t)=((d _(2,j+1) −d _(2,j))(t−t _(2,j))/(t _(2,j+1) −t _(2,j)))+d_(2,j)

Now that an approximation for d_(2,j) is known, the I-frame that isnearest to being d_(2,t) bytes from the beginning of the file containingthe recording of V₂ is used as the starting frame for playing back therecording for the viewer.

FIG. 12 shows a process flow in accordance with the embodiment describedherein. For the sake of clarity, the process has been illustrated with aspecific flow, but it should be understood that other sequences arepossible and that some may be performed in parallel, without departingfrom the spirit of the invention. In step 200, the system receives abroadcast including multiple perspectives of a program. The systempresents one of the perspectives to the viewer, step 210, and stores allof the perspectives in a storage device, step 220. In the embodimentdisclosed, the system stores all of the perspectives, but may beconfigured to selectively store perspectives based on criteria providedby the viewer (such as an indication of which, perspectives the vieweris interested in). The perspectives are stored in a circular buffer,step 260. Another perspective is presented to the viewer, step 230, andthe presentation of this perspective and the first perspective includespreparation of an audio/video signal for the television, step 250. Thepresentation of the other perspective in step 230 may involve searchingthe stored perspectives, step 240, and the perspective presented may beone of the stored perspectives.

A method and system for processing broadcasts have been disclosed.Software written according to the present invention may be stored insome form of computer-readable medium, such as memory or CD-ROM, ortransmitted over a network, and executed by a processor. Additionally,where methods have been disclosed, various sequences of steps may bepossible, and it may be possible to perform such steps simultaneously,without departing from the scope of the invention.

Although the present invention has been described in accordance with theembodiments shown, one of ordinary skill in the art will readilyrecognize that there could be variations made to the embodiments withoutdeparting from the scope of the present invention. Accordingly, it isintended that all matter contained in the above description and shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:
 1. A method comprising: receiving a program ofvisual content, the program comprising a plurality of visualperspectives being received simultaneously; displaying, using at leastone processor of a machine, a first one of the plurality of visualperspectives on a display device; displaying, using the at least oneprocessor of the machine, a second one of the plurality of visualperspectives on the display device during the displaying of the firstone of the plurality of visual perspectives; receiving a first usercommand to re-play a portion of the program; and in response to thefirst user command, re-displaying a first portion of the first one ofthe plurality of visual perspectives on the display device whilecontinuing to display the second one of the plurality of visualperspectives on the display device.
 2. The method of claim 1, whereinthe first one of the plurality of visual perspectives and the second oneof the plurality of visual perspectives are displayed in apicture-in-picture format.
 3. The method of claim 1, wherein: thereceiving of the program of visual content comprises receiving the firstone of the plurality of visual perspectives and the second one of theplurality of visual perspectives in a live broadcast of the program; andthe method further comprises: recording at least the first one of theplurality of visual perspectives to a data storage device; andretrieving, in response to the first user command, the portion of thefirst one of the plurality of visual perspectives from the data storagedevice.
 4. The method of claim 3, wherein the recording of at least thefirst one of the plurality of visual perspectives is to a circularbuffer of the data storage device.
 5. The method of claim 1, wherein thereceiving of the program of visual content comprises receiving the firstone of the plurality of visual perspectives and the second one of theplurality of visual perspectives from a data storage device.
 6. Themethod of claim 1, wherein the receiving of the program of visualcontent comprises receiving the first one of the plurality of visualperspectives and the second one of the plurality of visual perspectivesin a live broadcast of the program, and automatically recording thefirst one of the plurality of visual perspectives and the second one ofthe plurality of visual perspectives to a data storage device.
 7. Themethod of claim 1, wherein: prior to the first user command, the firstone of the plurality of visual perspectives and the second one of theplurality of visual perspectives represent a same portion of theprogram; and during the re-displaying of the first portion of the firstone of the plurality of visual perspectives, the second one of theplurality of visual perspectives represents a second portion of theprogram later in the program than the first portion of the program. 8.The method of claim 1, wherein: prior to the receiving of the first usercommand, the first one of the plurality of visual perspectives isdisplayed in a first region on the display device, and the second one ofthe plurality of visual perspectives is displayed in a second region onthe display device, the second region being larger in area than thefirst region; and the method further comprises: receiving, prior to thereceiving of the first user command, a second user command to swap thevisual perspectives on the display device; and in response to the seconduser command, displaying the second one of the plurality of visualperspectives within the first region, and displaying the first one ofthe plurality of visual perspectives in the second region.
 9. The methodof claim 1, wherein each of the plurality of visual perspectivescorresponds to a corresponding camera angle.
 10. A non-transitorycomputer-readable storage medium including instructions that, whenexecuted by at least one processor of a machine, cause the machine toperform operations comprising: receiving a program of visual content,the program comprising a plurality of visual perspectives being receivedsimultaneously; displaying a first one of the plurality of visualperspectives on a display device; displaying a second one of theplurality of visual perspectives on the display device during thedisplaying of the first one of the plurality of visual perspectives;receiving a first user command to re-play a portion of the program; andin response to the first user command, re-displaying a first portion ofthe first one of the plurality of visual perspectives on the displaydevice while continuing to display the second one of the plurality ofvisual perspectives on the display device.
 11. The non-transitorycomputer-readable storage medium of claim 10, wherein the first one ofthe plurality of visual perspectives and the second one of the pluralityof visual perspectives are displayed in a picture-in-picture format. 12.An apparatus comprising: at least one processor; and memory containinginstructions that, when executed by the at least one processor, causethe apparatus to perform operations comprising: receiving a program ofvisual content, the program comprising a plurality of visualperspectives being received simultaneously; displaying a first one ofthe plurality of visual perspectives on a display device; displaying asecond one of the plurality of visual perspectives on the display deviceduring the displaying of the first one of the plurality of visualperspectives; receiving a first user command to re-play a portion of theprogram; and in response to the first user command, re-displaying afirst portion of the first one of the plurality of visual perspectiveson the display device while continuing to display the second one of theplurality of visual perspectives on the display device.
 13. Theapparatus of claim 12, wherein: the receiving of the program of visualcontent comprises receiving the first one of the plurality of visualperspectives and the second one of the plurality of visual perspectivesin a live broadcast of the program; and the operations further comprise:recording at least the first one of the plurality of visual perspectivesto a data storage device; and retrieving, in response to the first usercommand, the portion of the first one of the plurality of visualperspectives from the data storage device.
 14. The apparatus of claim12, wherein: prior to the receiving of the first user command, the firstone of the plurality of visual perspectives is displayed in a firstregion on the display device, and the second one of the plurality ofvisual perspectives is displayed in a second region on the displaydevice; and the operations further comprise: receiving, prior to thereceiving of the first user command, a second user command to swap thevisual perspectives on the display device; and in response to the seconduser command, displaying the second one of the plurality of visualperspectives within the first region, and displaying the first one ofthe plurality of visual perspectives in the second region.
 15. Theapparatus of claim 14, the first region being larger in area than thesecond region.